Device for measuring the visual attention of subjects for a visible object

ABSTRACT

In order to measure the visual attention of persons or animals to a visible object, a beam (9) is radiated to an area of observation (1) including the persons or animals under test. A measuring arrangement in close vicinity to the object comprises a radiation source (1) emitting, e.g. an invisible parallel beam (9), a scanning member (3), guiding said radiation beam (9) across the area of observation (1) and detector means (6, 7) receiving the radiation scattered from the area of observation (1). Radiation from the retina and/or cornea of said persons or animals is selectively detected and transformed into an evaluation signal.

The invention relates to a method as well as a device for measuring thevisual attention of persons or animals for a visible object. Here, theterm "object" should be interpreted in a broad sense. Thus, itcomprises, among other things, material objects, such as products placedin shops or department stores, museum and exhibition works, e.g. with aview to the protection thereof, security apparatus, in order todetermine whether there is a suspicious interest for said items, etc.Further, advertising in the most general sense, e.g. advertisementprogrammes, commercials, posters, advertisement bills, billboards, etc.Furthermore, it comprises "living objects", both human beings andanimals, in which the attraction exerted on them must be measured.

In research of consumer behaviour, one generally employs methods anddevices, through which no data can be produced without activecooperation of the respondent. It is true, that selected testees orrespondents are of course willing to cooperate, but such a method hasthe disadvantage, that one is fully dependent on the faultlesscooperation of the respondents. That is the reason why the results arenot reliable.

For evaluating the marketability of a product placed in a departmentstore, videocameras recording potential customers are used. From therecorded images it is determined to what extent the product to beevaluated attracts the attention of the public. Here, a disadvantage isthat the use of videocameras infringes the privacy of arbitraryspectators, and that furthermore evaluating the recorded images istime-consuming and inaccurate.

According to the invention, a method has been developed for measuringthe visual attention of persons or animals for a visible object, inwhich all of the above disadvantages have been avoided.

The method according to the invention is characterized in that from thevicinity of the object, a radiation beam is sent out to an observationarea, where persons or animals are present, and that radiation reflectedat the retina of the eyes is selectively detected and is transformedinto an evaluation signal.

Since visible radiation might have a disturbing influence on the public,non-visible radiation is preferable. The method according to theinvention at one hand has the advantage, that no active cooperation ofrespondents is required, yet only passive cooperation of arbitrarypersons or animals, through which reliable information can be provided.Furthermore, there is no infringement of privacy, since only reflectionsof the eye are the standard for the measurement.

The invention efficiently employs the principle of retro-reflection ateyes, known per se, which can be realized in many ways and occurs whentaking pictures with flashlight, among other things. When a person oranimal turns his eyes to the flashlight, the light reflected at the eyeswill be caught by the camera objective and cause (over)exposure at theposition where the eyes fall on the film image of the camera. With theinvention, this retro-reflection is efficiently employed, in order todetermine, whether or not a person or animal present in a chosen area ofobservation is looking at the object to be evaluated.

According to the invention, it is possible to realize the evaluation insuch a way, that the area of observation is covered by radiation whichis received by suitable receiving systems.

However, it is also possible to employ a scanning beam covering the areaof observation stepwise. With this method, the method is characterizedin that the radiated beam is a substantially parallel beam being ledscanningly across the area of observation, and that e.g. radiationreflected coaxially with the scanning beam is selectively detected andis taken as a standard for radiation reflected at the retina of eyes.

The radiation reflected coaxially with the scanning beam will then besaid radiation retro-reflected at the pupil of the eye.

However, it is also possible to work with the radiation reflections onthe cornea. With this method, the invention is characterized in that theradiation transmitted from the source of radiation and/or recording unitpositioned near the object, reflected on the cornea of human being oranimal, is received by the recording unit.

The recording unit, with or without amplification of radiation, musthave a sensitivity and/or resolution high enough to determine thereflections. The resolution can be enhanced with the help of a device insuch a way that a number of times per time unit, the sensor receives apart of an image being large enough. Enlarged recording of parts of animage can take place in a number of ways, e.g. with the help of a deviceby which a number of image portions are displayed, whether or notsimultaneously, on said sensor in combination with a selection device,as a result of which a portion can always be measured individually.

The recording systems can be effected in many ways. By detectors, forexample, including photo detectors; sensors including CCD sensors;detectors and sensors in combination with a display device, includingoptics; ultra-sensitive systems, including cameras, video cameras, etc.;systems having spectral sensitivity and/or resolution, includingcolour-sensitive or color-distinguishing cameras; combinations ofdifferent types of detectors and sensors functioning simultaneously orin a certain sequence, and each partly contributing to the evaluationsignal. The sources or radiation can also be realized in many ways. Forexample, by means of light sources for visible light, UV or infraredlight; sources of other types of radiation, including radar, sonar orcentimeter waves; monochrome or spectral sources; coherent ornon-coherent sources; modulated, continuous, of pulse sources; spatialor point sources.

The radiation beam too, can be realized in many ways.

For example, diverging, converging, focussed, collimated or diffuse.

In all cases, by way of the information obtained, it can be determined,e.g. through coaxial retroreflection at the retina, whether or notpersons watched the object to be evaluated. It goes without saying, thatwhatever the circumstances, it is required that the beam is, at leastvirtually, is emitted from the vicinity of the object, so that lookingin the immediate surroundings of the object will mean that the person isactually watching the object.

For effecting the method, in which the area of observation is scanned bya parallel beam, the invention provides for a device, characterized by aradiation source having a substantially parallel beam, a scanningmember, scanningly guiding said beam over the area of observation, adetector member, arranged such, that it receives the radiation reflectedin the direction of the incident radiation in the area of observationand e.g. distinguishes coaxial radiation from non-coaxial radiation.

Efficiently, the invention can be such, that the detector member has abeam separator, consisting of a reflector unit mounted therein, arrangedat an angle of e.g. 45° in relation to the beam path of the reflectedradiation and being provided with a central passage for passing coaxialradiation, for example, and two detectors, mounted for receiving thepassed radiation and the radiation reflected by the deflection member,respectively, and that the respective outputs of the two detectors areconnected to respective inputs of a subtracting member. The subtractingmember can be realized in many ways, e.g. by means of a differentialamplifier. A differential amplifier, representing a substracting circuitsubstracting the output voltage signals of the two, is very advantageousand provides a signal, in which the non-coaxial radiation, which is infact the background noise, is substantially eliminated. After all, thisbackground noise is also present in the e.g. coaxially passed radiation,and by substracting said two signals, the pure e.g. coaxial radiationremains, which is the actual standard for retroreflection at the retinain the area of observation.

With a view to the positioning of the detector member, it is preferable,that a partly transmitting deflection member is mounted at an angle ofe.g. 45° in the radiation path between radiation source and scanningmember, said deflection member deflecting the returning reflectedradiation towards said detector member.

Basically, the signal obtained at the output of the differentialamplifier can be further analysed by computer means. It is alsopossible, to connect the output of the differential amplifier to the oneinput of a comparator circuit, with a reference being connected to theother input, which represents a condition, property or threshold valuefor eyes whether or not looking at the object to be evaluated. Further,as source of radiation, one could efficiently employ a source having anon-detectable low power radiation. Low power is desired, since a sourceof radiation which is too strong, might cause damage to eyes.

In order to apply the first method, in which all of the area ofobservation is irradiated by a beam, the invention provides for a devicecharacterized by a recording unit for receiving radiation reflected atthe area of observation, a pulse radiation system sychronized to therecording system for pulse-wise irradiation of the area of observation,and means for distinguishing signals recorded by the recording systemfrom radiation reflected at the retina of eyes of persons or animalsbeing in the area of observation.

By the fact, that the retroreflected radiation at the pupils of theeyes, looking in the direction of the object, is considerably strongerthan the remaining, non-coaxial reflection, these pupils becomesignificant on the recordings, in which coaxially reflected radiation isrecorded (so-called "brightness pupils"), for example. This offers anumber of possibilities for evaluating suitable viewing information fromit.

There are number of possibilities for effecting such a device. Thus, thedevice can be designed such, that the recording system consists of onerecording unit, and the pulse radiation system consists of one source ofradiation having its pulse time synchronized with the recording time ofthe recording system, and that the pulse source is arranged transverselyto the radiation path between recording optics and area of observation,a partly transmitting deflection member being positioned in saidradiation path, said deflection member deflecting the radiation of thesource of radiation in the direction of the radiation path to the areaof observation.

In this embodiment, both background radiation and e.g. coaxial radiation(brightness pupils) will be combined in each image recording. In orderto clearly distinguish the brightness pupils, it is preferred that therecording system is a colour recording system, that the pulse source isa source of soft, detectable radiation, and that there are means foranalysis of the recorded spectral images. After all, the brightnesspupil images represent predominantly the red component in the recording,and by an analysis of the red of the recordings, which can take placeeasily with the help of suitable computer means, it can be deducted, towhat extent persons watched the object to be evaluated.

Another embodiment of the device according to the invention ischaracterized in that the recording system consists of one recordingunit, and the pulse system consists of a first and a second pulsesource, having their pulse times alternately synchronized with therecording time of the recording system, that the first pulse source isarranged next to the recording system for irradiating the area ofobservation with radiation, which is not coaxial to the radiation pathbetween recording optics and area of observation, and that the secondpulse source is arranged transversely to said radiation path, in which apartly transmitting deflection member has been positioned, whichdeflects the radiation of the second pulse source in the direction ofthe radiation path to the area of observation, and that there is asubstracting circuit, coupled to the output of the recording system,said substracting circuit subtracting subsequently recorded imagesignals.

With this embodiment, the recording system alternately makes recordingsof images caused by the first pulse source and images caused by thesecond pulse source. However, since no or hardly any coaxialretroreflection is possible with irradiation by the first pulse source,recordings are made without brightness pupils in them. On the otherhand, the second pulse source is capable of sending pulses, thereflected radiation thereof e.g. also containing coaxialretroreflection, to the area of observation. Therefore, with the help ofthe second pulse source, recordings also containing the brightnesspupils of viewers are made. By subtracting the images with and withoutthe brightness pupils from each other in the subtracting circuit, onefinally obtains image signals which contain only the brightness pupildata, and can be taken as a measure for the number of people or animalsviewing.

Another possibility for a device according to the invention ischaracterized in that the recording system has a first and a secondrecording unit, arranged at a short distance from each other in such away, that the radiation path between the area of observation and thefirst recording system is slightly shifted in relation to that which isbetween the area of observation and the second recording unit, that therecording system has one pulse source, its pulse time being synchronizedwiht the recording time of the first and second recording unit, andarranged transversely to the radiation path between area of observationand first recording system, and that a partly transmitting deflectionmember is mounted in said radiation path, said deflection memberdeflecting the pulse source radiation in the direction of the radiationpath to the area of observation, and that the outputs of the first andsecond recording unit are connected to the respective inputs of asubtracting circuit.

In contrast to the previous embodiment, with this embodiment, not thepulse radiation as such, but the arrangement of the two recording unitsis responsible for the selection in images with and without brightnesspupils. With this arrangement, only the radiation of the first recordingunit is capable of e.g. receiving coaxially reflected radiation, and bysubstracting the outputs of both recording units from each other in asubtracting circuit, just like in the previous case, again an imagesignal can be obtained, which is exclusively indicative of theretroreflection of persons viewing the object to be evaluated.

Yet another embodiment of the device according to the invention ischaracterized in that the recording system has a first and a secondrecording unit, and the pulse system consists of a first and a secondpulse source, that the first pulse source is synchronized with the firstrecording unit, and the second pulse source is synchronized with thesecond recording unit, in such a way, that alternately the first camerarecords radiation of the first pulse source reflected from the area ofobservation and the second recording unit records radiation of thesecond pulse source reflected from the area of observation, in which thefirst pulse source is positioned non-coaxially in relation to therecording system arrangement and provides a radiation beam, which is notreflected coaxially from the area of observation to the first recordingunit, and the second pulse source e.g. is positioned coaxially inrelation to the recording system arrangement and provides a radiationbeam, which is e.g. reflected coaxially from the area of observation tothe second recording unit, and that the outputs of the first and secondrecording units are connected to the respective inputs of a subtractingcircuit.

The essence of this embodiment is that there are two viewing systems,which do not see each other, one of them being able to detectretroreflections and the other one not.

In this case too, a clear image of the recorded brightness pupils can beachieved by subtracting the two images from each other.

The invention will now be explained further by means of the drawing. Inthe drawing:

FIG. 1 shows diagrammatically in block shape a first embodiment of thedevice according to the invention, operating according to the scanningprinciple;

FIG. 2 shows a second embodiment of the device according to theinvention, operating with the help of image recordings;

FIG. 3 shows a recording of "brightness" pupils obtained by said device;and

FIG. 4 shows a third embodiment of the device according to theinvention, also operating with image recording.

As stated before, the invention is based on the principle ofretroreflection at the eyes of persons or animals viewing.Retroreflection means, that the radiation incident on eye pupils isreflected in the same direction as the one in which it incides. When theincident radiation actually or virtually comes from an object to beevaluated, the retroreflection will naturally be a standard for thefact, whether a person or animal in a certain area of observation islooking in the direction of the incident radiation and thus also in thedirection of the object. By providing for, that a detector is positionedin such a way, that said retroreflected radiation can be collected, itis possible to measure the attention of persons or animal in a certainarea of observation from it.

FIG. 1 shows a first embodiment of the device, in which saidretroreflection can be determined. In FIG. 1, 1 indicates an area ofobservation, from which persons can view a visible object. In the closevicinity of said object not shown in the drawing, a first measuringarrangement according to the invention is mounted. It has a radiationsource 2, preferably a source of invisible radiation, since visibleradiation might undesirably attract attention, or hinder it. Theradiation should not be focussed too strong, and also the radiationcapacity must be low, in order to prevent possible damage to the eyes. Ascanning member 3 receives the radiation beam and deflects it in thedirection of the area of observation 1. In doing so, a scanning movementis made across 120° in the example shown, in one or more directions, asa result of which subsequently the total area of observation is coveredby the radiation beam. The scanning member 3 can be a mechanical oropto-mechanical scanner, e.g. one that operates with a polygonal mirrorwheel and a servo mirror, or an electronic or opto-electronic scanner,or otherwise.

Between the radiation source 2 and the scanning member 3 there is apartly transmitting deflection member 4, deflecting the returning,reflected radiation to a detector system, consisting of a centrallybored, e.g. 45° deflection member 5, a first detector 6 for receivingdeflected radiation, and a second detector 7 for receiving radiationtransmitted through the central bore of the deflection member. Theoutputs of the first detector 6 and the second detector 7 are connectedto both inputs of a differential amplifier 8.

Said device operates as follows. The radiation source emits a focussedmeasuring beam to the scanning member 3, its output radiation beam 9scanning the area of observation 1 across e.g. 120°. The radiationreflected there returns to the scanner and according to the path of theradiation source it goes to the partly transmitting deflection member 4deflecting the reflected radiation to the centrally bored e.g. 45°deflection member 5. Owing to this, e.g. coaxial radiation will passthrough the bore to the detector 7, whereas non-coaxial radiation willbe reflected to the detector 6 by the deflection member 5. Thus, one canefficiently make a division between e.g. coaxial radiation andnon-coaxial radiation, in the sense, that substantially non-coaxialradiation is able to reach the detector 6. The e.g. coaxially reflectedradiation is now a standard for retroreflection at eyes in the area ofobservation and in this way, one can divide between coaxially andnon-coaxially reflected radiation. Since the detector, apart fromcoaxial radiation, also receives non-coaxial radiation, the outputs ofboth detectors are connected to the inputs of a substracting member, inthe illustrated embodiment shown as differential amplifier 8. The outputsignal of said differential amplifier can be processed further, e.g. bysuitable computer programs. In the illustrated embodiment, this isindicated diagrammatically by the comparator circuit 10, in which saidoutput signal is compared to a reference signal Y. In this way, signalscan be obtained which are indicative of the attention persons give anobject to be evaluated.

Another possibility is employing non-visible pulse radiation, andrecording systems.

An example of such a device is shown in FIG. 2. There, 11 indicates afirst pulse source (infrared) and 12 indicates a second pulse source.The radiation of the first pulse source 11 travels through an opticalelement 13 to a partly transmitting deflection member 14, in order todeflect the radiation to the area of observation 1. Through a deflectionmember 15 between said first pulse source and said optical element 13,the radiation of the second pulse source 12 is deflected into thedirection of said optical element. Radiation reflected at the area ofobservation returns through the partly transmitting deflection member 14and through an optical element 16, it reaches a recording systemcomprising a laterally arranged first recording unit 17, a transverselyarranged second recording unit 18 and a beam splitter 19, splitting thereflected incident beam into two partial beams, reaching the respectiverecording units 17 and 18. In this embodiment, both recording units haveone common optical element 16. The outputs of both recording units arein turn connected to a substracting circuit, shown as differentialamplifier 8. Both pulse sources are connected to an electronic switch20, e.g. a bistable vibrator. A sync pulse generator 21 is at one sideconnected to the electronic switch 20, at the other side to bothrecording units 17 and 18.

Said device operates as follows: the first pulse source 11 transmitsnon-coaxial, non-focussed pulses, synchronous to the recording time ofsaid first recording unit 18. The sync pulse generator 21 controls thisworking in such a way, that opening and closing of the respectiverecording units 17 and 18 occurs in succession. There, the generator 21generates vertical synchronizing pulses VS, an example of which beingindicated at the bottom of the drawing. Said synchronizing pulses VS areapplied to the first and second recording unit 17 and 18, respectively.These are set in such a way, that e.g. a valve is opened under thecontrol of a falling and rising flank of said synchronizing pulse,respectively. Opening and closing of e.g. a valve of the first andsecond recording units, respectively, takes place under control of e.g.a clock signal synchronized with the synchronizing signal VS. Throughthe electronic switch 20, such working takes place in order to controlthe pulse sources 11 and 12 synchronously with the recording units 17and 18.

In this way, it is achieved, that recording unit 17 can only receiveradiation from the non-coaxial radiation source 12. However,retroreflection in the area of observation is only possible with thecoaxial radiation of radiaton source 12, and recording unit 18 makesrecordings, in which the eyes of persons or animals viewing are depictedextremely bright; so-called brightness pupils. On the other hand,recording unit 17 does not receive said brightness pupils, and bysubtracting the outputs of recording units 17 and 18 in the differentialamplifier 8, an output image signal exclusively or substantiallyconsisting of brightness pupils is obtained. Since persons or animalsnot watching straight at the object can cause some "brightness" as well,it is necessary, that the signals obtained are further screened onrelevance, which can be effected by suitable computer processing. In thedrawing, this is illustrated diagrammatically by the comparator circuit16.

Further, in FIG. 2, a limitation, e.g. a diaphragm, 22 is illustrated,which functions to adjust the beam of reflected radiation to thediameter of the optical element 13 of the incident radiation. Further,23 indicates a radiation dimmer for excluding lateral reflectioneffects.

FIG. 3 shows a recording obtained with such a device, in which the pairsof dots represent the so-called brightness pupils. It will be obvious,that viewing data can be obtained from such data.

FIG. 4 is a simplified embodiment of the device according to theinvention, in which two recording units and one single pulse source areemployed. There, both recording units 17 and 18 are arranged at adistance of at least 6 mm opposite each other with their receivingopenings facing each other. Deflection members 24 and 25 provide for theradiation paths of the recording units are led to the area ofobservation 1, said radiation paths being slightly displaced in relationto each other. A partly transmitting deflection member 27 is arranged onthe axis of the radiation path of recording unit 18, e.g. at an angle of45° in relation to the axis direction of the radiation path of saidrecording unit. A pulse source 26, preferably of invisible radiation, isarranged next to the recording unit 18 in such a way, that through thedeflection member 27, its radiation is deflected according to thedirection of the radiation path of said recording unit. The pulse source26 is synchronized with both recording units 17 and 18 in a way notindicated.

This device is based on the principle, that only the recording unit 18is capable of receiving retroreflected radiation from the area ofobservation 1, which is not possible with the recording unit 17, sincethe latter has no suitable arrangement relation with pulse source 26 tothat end. Therefore, apart from its ability to receive backgroundradiation, the second recording unit 18 is also capable of receivingradiation of brightness pupils, such as e.g. coaxial retroreflection,whereas the first recording unit 17 receives background radiation only.The outputs of both recording units 17 and 18 are in turn coupled to asubtraction circuit not shown, by which, just like with the device ofFIG. 2, recordings can be obtained, that show brightness pupils only,which can be taken as a standard for the public watching the object. Inthis case too, it can be necessary to dim the radiation with the help ofa radiation dimmer 15.

In the above, the invention has been explained by way of a number ofexamples. However, it will be obvious, that the invention is not limitedto these specific examples, nor to the principle of retroreflection, butthat there are many possibilities for applying the invention. A numberof those have been discussed in the first part of the descriptiveportion. Further embodiments and possibilities will be clear to theexpert by way of description and claims.

I claim:
 1. A device for measuring the visual attention of persons oranimals for an object, comprising:a radiation member for supplyingradiation; a scanning member, scanningly guiding the radiation of theradiation member across an area of observation; a detector member, saiddetector member having a beam separator, including a reflector unitmounted therein, arranged at an angle in relation to a beam path ofradiation reflected from the area of observation and having at least twodetectors mounted for receiving the radiation transmitted by said beamseparator and the radiation reflected by said beam separator,respectively; and a subtracting member having respective inputselectrically connected to respective outputs of said at least twodetectors.
 2. The device according to claim 1, wherein said detectormember includes a reflector unit mounted therein, and a central passagefor passing coaxial radiation.
 3. A device according to claim 2, furthercomprising a partly transmitting deflection member mounted at an anglein the radiation path between said radiation member and said scanningmember, said partly transmitting deflection member deflecting thereturning reflected radiation towards said detector member.
 4. Thedevice according to claim 1, further comprising a partly transmittingdeflection member mounted at an angle in the radiation path between saidradiation member and said scanning member, said partly transmittingdeflection member deflecting the returning reflected radiation towardssaid detector member.
 5. The device according to claim 1, wherein anoutput of said subtracting circuit is connected to one input of acomparator circuit, with a reference signal being connected to an otherinput of said comparator circuit.
 6. A method for measuring the visualattention of persons or animals for an object, comprising:a)transmitting, from a position near the object, at least one beam ofradiation from at least one radiation member into an area of observationwhere moving persons or animals are present; b) detecting radiationreflected from the area of observation with at least one signal detectormember; c) arranging said at least one radiation member and said atleast one signal detector member to distinguish coaxial radiationreflected from the area of observation from non-coaxial radiationreflected from the area of observation; and d) transforming the coaxialradiation, indicative of radiation reflected at the retina and/or thecornea of eyes of the moving persons or animals, into an evaluationsignal.
 7. The method according to claim 6, wherein said transmittingstep includes scanning the at least one beam of radiation across thearea of observation, the at least one beam of radiation being asubstantially parallel beam.
 8. The method according to claim 6, whereinthe at least one beam of radiation is a pulsed beam, transmittedaccording to pulse cycles into the area of observation.
 9. A device formeasuring the visual attention of persons or animals for an object,comprising:a signal recording system for receiving radiation reflectedfrom an area of observation where persons or animals are present; aradiation pulse system, synchronized to said signal recording system,for pulsewise irradiation of the area of observation; and means fordistinguishing, in signals recorded in said signal recording system,radiation reflected by a retina or a cornea of eyes of persons oranimals in the area of observation from radiation reflected by otherobjects in the area of observation.
 10. The device according to claim 9,wherein said signal recording system includes one recording unit, andsaid radiation pulse system includes one pulse source of radiationhaving its pulse time synchronized with the recording time of saidsignal recording system, said pulse source of radiation being arrangedtransversely to the radiation path between recording optics and the areaof observation, a partly transmitting deflection member being positionedin the radiation path, said partly transmitting deflection memberdeflecting the radiation of said pulse source of radiation in thedirection of the radiation path to the area of observation.
 11. Thedevice according to claim 9, wherein said signal recording systemincludes one recording unit, and said radiation pulse system includes afirst pulse source and a second pulse source, having their pulse timesalternately synchronized with the recording time of said signalrecording system, said first pulse source being arranged relative tosaid signal recording system for irradiating the area of observationwith radiation being non-coaxial to the radiation path between recordingoptics and the area of observation, and said first pulse source beingarranged transversely to a radiation path in which a first deflectionmember has been positioned, said first deflection member deflecting theradiation of said second pulse source in the direction of the radiationpath to the area of observation, andwherein said device furthercomprises a subtracting circuit, coupled to the output of said signalrecording system, said subtracting circuit subtracting subsequentlyrecorded signals.
 12. The device according to claim 11, wherein saidfirst deflection member is positioned in the radiation path of saidfirst pulse source and deflects radiation of said second pulse sourceinto the radiation path of said first pulse source, and wherein saiddevice further comprises a second deflection member positioned in theradiation path between the area of observation and said one recordingunit to deflect radiation from said first or second pulse sources to thearea of observation.
 13. The device according to claim 11, furthercomprising a comparator circuit, and wherein an output of saidsubtracting circuit is connected to one input of said comparatorcircuit, with a reference signal being connected to an other input ofsaid comparator circuit.
 14. The device according to claim 9, whereinsaid signal recording system has a first recording unit and a secondrecording unit, arranged at a short distance from each other in such away that the radiation path between the area of observation and saidfirst recording unit is slightly shifted in relation to that which isbetween the area of observation and said second recording unit, saidradiation pulse system having one pulse source, its pulse time beingsynchronized with the recording time of said first and second recordingunits, said radiation pulse system being arranged transversely to theradiation path between the area of observation and said first recordingsystem,wherein said device further comprises a partly transmittingdeflection member mounted in the radiation path, said partlytransmitting deflection member deflecting the pulse source radiation inthe direction of the radiation path to the area of observation, andwherein said device further comprises a subtracting circuit havingrespective inputs electrically connected to respective outputs of saidfirst and second recording units.
 15. The device according to claim 14,wherein, together with a beam separator, said first and second recordingunits positioned at an angle to each other form said signal recordingsystem having a common radiation path between the area of observationand said signal recording system.
 16. The device according to claim 14,further comprising a comparator circuit, and wherein an output of saidsubtracting circuit is connected to one input of said comparatorcircuit, with a reference signal being connected to an other input ofsaid comparator circuit.
 17. The device according to claim 9, whereinsaid signal recording system includes a first recording unit and asecond recording unit, and said radiation pulse system includes a firstpulse source and a second pulse source, said first pulse source beingsynchronized with said first recording unit and said second pulse sourcebeing synchronized with said second recording unit such that alternatelysaid first recording unit records radiation of said first pulse sourcereflected from the area of observation and said second recording unitrecords radiation of said second pulse source reflected from the area ofobservation, in which said first pulse source is positionednon-coaxially in relation to said signal recording system and provides aradiation beam that is not reflected coaxially from the area ofobservation to said first recording unit, and said second pulse sourceis positioned coaxially in relation to said signal recording systemarrangement and provides a radiation beam that is reflected coaxiallyfrom the area of observation to said second recording unit, andwhereinsaid device further comprises a subtracting circuit having respectiveinputs electrically connected to respective outputs of said first andsecond recording units.
 18. The device according to claim 17, wherein,together with a beam separator, said first and second recording unitspositioned at an angle to each other form said signal recording systemhaving a common radiation path between the area of observation and saidsignal recording system.
 19. The device according to claim 17, furthercomprising a first deflection member positioned in the radiation path ofsaid first pulse source, said first deflection member deflectingradiation of said second pulse source into the radiation path of saidfirst pulse source, and further comprising a second deflection memberpositioned in the radiation path between the area of observation andsaid signal recording unit to deflect radiation from said first orsecond pulse sources to the area of observation.
 20. The deviceaccording to claim 17, further comprising a comparator circuit, andwherein an output of said subtracting circuit is connected to one inputof said comparator circuit, with a reference signal being connected toan other input of said comparator circuit.
 21. The device according toclaim 9, further comprising at least two discrete members in anintegrated form.
 22. The device according to claim 9, further comprisingat least two optical components in an integrated form.
 23. A device formeasuring the visual attention of persons or animals for an object,comprising:an irradiation system near the object for irradiating visibleradiation into an area of observation where persons or animals arepresent; at least one of a spectral sensitive signal recording systemand a spectral selective signal recording system for receiving radiationradiated from said irradiation system and reflected at said area ofobservation, the radiation being reflected at the retina or cornea ofeyes of persons or animals in the area of observation; and means for redanalysis to distinguish the signals recorded in said signal recordingsystem.
 24. The device according to claim 23, further comprising atleast two discrete members in an integrated form.
 25. The deviceaccording to claim 23, further comprising at least two opticalcomponents in an integrated form.